The invention relates to clutches in general, and more particularly to improvements in clutches which are to be used in hydrodynamic torque converters, especially in torque converters for use in motor vehicles. Still more particularly, the invention relates to torque transmitting units, such as clutch discs or clutch plates, which can be used in the clutches of torque converters.
As a rule, the clutch plate of a clutch in a hydrodynamic torque converter is installed in a substantially shell-shaped input member which is connectable with the engine of the motor vehicle. Such clutch plate normally comprises at least one so-called hub disc, a second disc at one side of the hub disc, a piston like input element which is non-rotatably connected with the second disc, and one or more resilient elements which operate between and in the circumferential direction of the discs to oppose angular movements of the input element and the hub disc relative to each other. Reference may be had, for example, to Koshimo U.S. Pat. No. 4,576,260, Niikura, et al., U.S. Pat. No. 4,577,737, Pickard et al., U.S. Pat. No. 4,580,668 and Stockton et al., U.S. Pat. No. 4,608,032.
A different clutch is disclosed in Malloy U.S. Pat. No. 4,423,803. This clutch employs a clutch plate with a viscous shear clutch between the input and output elements of the clutch plate. The clutch of Malloy further employs a diaphragm spring which reacts against the turbine member of the hydrodynamic torque converter and serves to apply an axial force against a substantially piston-like input element of the clutch plate. In addition, the piston-like input element forms part of a friction clutch and is biased axially against a friction surface which is provided on the input member of the torque converter. The diaphragm spring ensures very rapid and smooth engagement of the torque converter clutch. A drawback of the torque converter clutch of Malloy is that the diaphragm spring is a separate part which is not directly or indirectly coupled to any other part of parts of the clutch or torque converter. Such diaphragm spring must be installed in a separate step. This contributes to the cost of the clutch. In addition, the entire clutch becomes inoperative if the diaphragm spring is accidentally omitted during assembly of the torque converter and its clutch.